Production of optical elements

ABSTRACT

A method of making an optical element that includes a thermoplastic power portion, the method including laminating a first thermoplastic sheet to one side of a functional film, laminating a second thermoplastic sheet to a second side of the functional film, and affixing either the first thermoplastic sheet or the second thermoplastic sheet to the power portion, with the other of the first or second thermoplastic sheets being open to atmosphere.

This is a Divisional of application Ser. No. 08/397,949, filed Mar. 3,1995.

BACKGROUND OF THE INVENTION

The present invention generally relates to an optical element and to amethod of making an optical element. More specifically, the presentinvention relates to an optical element that incorporates a functionalproperty and to a method of incorporating the functional property in theoptical element.

Manufacturers have encountered and overcome numerous technicalchallenges presented by chemical compounds that are newly incorporatedinto optical elements, such as ophthalmic lenses. First, there were newformulations for inorganic glasses. These new glass formulationsrequired development of new processing steps and conditions, as well as,new grinding and polishing techniques. Later, the industry focus shiftedto thermoset plastics, such as allyl diglycol carbonate, which is soldunder the CR-39® trademark of PPG Industries, Inc. One of the morerecent developments involves manufacture of ophthalmic lenses usingthermoplastic materials, such as polycarbonate.

Polycarbonate is an amorphous, thermoplastic material that hasmechanical properties which are very desirable for ophthalmic lenses.For example, ophthalmic lenses made of polycarbonate have unusually highimpact resistance and strength which make the lenses surprisinglyshatter-resistant. Also, the relatively low specific gravity ofpolycarbonate makes it possible to significantly decrease the weight ofpolycarbonate lenses, as compared to glass or CR-39® lenses.Polycarbonate also is highly transparent and has a desirably highrefractive index for ophthalmic lens applications. Furthermore, the goodthermal properties of molten polycarbonate makes the material conduciveto efficient processing by conventional techniques, such as injectionmolding.

Despite the advantages of the material, incorporation of polycarbonateinto ophthalmic lens manufacture has not been without problems. Forexample, the hardness of the material necessitated development ofdifferent grinding and polishing techniques from techniques used forglass and CR-39® lenses. Additional challenges remain that have not beensatisfactorily addressed to date. These challenges relate toincorporation of functional properties into lenses made ofpolycarbonate. Functional properties include features, such asfiltering, cosmetic and durability features, that may be incorporatedinto an optical lens to impart or modify lens characteristics, otherthan optical power or magnification characteristics. Some examples offunctional properties include light polarization, photochromism, tint,color, decor, indicia, hardness, and abrasion resistance.

There are various examples of shortcomings relating to polycarbonateophthalmic lenses and to techniques for manufacturing polycarbonateophthalmic lenses. For example, no method presently exists for makingpolarized polycarbonate lenses capable of meeting ophthalmicprescription specifications--that is, creating polarized polycarbonatelenses with different focal powers. Also, no method presently exists forquickly and efficiently making high quality photochromic polycarbonatelenses. Furthermore, no method is available for efficiently andeffectively incorporating functional properties into ophthalmic lensesmade of new materials or materials that have not yet been adapted toophthalmic lens manufacture.

Numerous methods for incorporating polarizing properties into lensesmade of material other than thermoplastic material are known. Forexample, U.S. Pat. No. 3,051,054 to Crandon describes a method ofproviding a glass lens with a film of light-polarizing material. Also,U.S. Pat. No. 4,495,015 to Petcen describes a method of laminating athermoset/thermoplastic wafer to an ophthalmic glass lens.

Various patents disclose methods of incorporating a polarizing film orwafer within a lens cast of thermoset material. For example, U.S. Pat.No. 3,786,119 to Ortlieb discloses a laminated plate of polarizingplastic material that is formed into a polarizing screen. The polarizingscreen is placed within a mold which is filled with polymerizable orpolycondensible liquid resin. U.S. Pat. No. 3,846,013 discloses alight-polarizing element formed by sandwiching light-polarizing materialbetween thin layers of optical quality transparent polymeric material.The light-polarizing element is placed within a mold, and apolymerizable monomer is placed in the mold on either side of thelight-polarizing element.

Also, U.S. Pat. No. 3,940,304 to Schuler discloses a shapedlight-polarizing synthetic plastic member that is disposed betweenlayers of an optical quality synthetic monomeric material in a mold. Amonomeric material is placed within the mold and polymerized to form acomposite synthetic plastic light-polarizing lens structure. U.S. Pat.No. 4,873,029 to Blum discloses a plastic wafer that may includepolarizing features. The plastic wafer is inserted into a mold betweenliquid monomer molding material. The mold is then subjected tooven-curing to polymerize the liquid monomer. Additionally, U.S. Pat.No. 5,286,419 to van Ligten et al. discloses a shaped polarizing filmthat is embedded in pre-gelled resin. The resin is cured to form a lightpolarizing lens.

However, despite the availability of these methods for incorporating apolarizing film or wafer within a lens cast of thermoset material, aneed remains for an improved polarizing lens. For example, delaminationof cast polarizing lenses remains a significant problem. Also, castlenses are relatively heavy and offer less than adequate levels ofimpact and shatter resistance. Finally, manufactures continue toencounter difficulties making polarizing cast lenses with optimumrefractive index values.

Another reference, U.S. Pat. No. 5,051,309 to Kawaki et al., concerns apolarizing plate that is made by laminating polycarbonate film on bothsides of a polarizing thin layer. The polarizing thin layer is composedof a polymeric film and a dichroic dye oriented on the polymeric film.According to the patent, suitable uses of the polarizing plate includegoggles and sunglasses. However, the polarizing plate of U.S. Pat. No.5,051,309 would not be suitable for use as an optical lens capable ofmeeting ophthalmic prescription specifications. For example, thepolycarbonate film included in the polarizing plate of this patent lacksthe material integrity needed for successful grinding and polishing ofpolycarbonate optical elements to prescription specifications.Polycarbonate that is ground and polished to make optical elements musthave sufficient material integrity to withstand the heat and pressuregenerated during grinding and polishing operations. The lack of materialintegrity of the polycarbonate film used in the Kawaki polarizing platewould affect cosmetic properties, as well as, the impact strength of anyprescription specification optical elements made by grinding andpolishing the polycarbonate film.

As noted, another challenge concerns incorporation of photochromicproperties into polycarbonate lenses. For example, present polycarbonatelenses that include photochromic material offer marginal, and evenunacceptable, photochromic properties and cosmetic qualities. Indeed, nomethod presently exists for making high quality photochromicpolycarbonate lenses.

Two current methods of incorporating organic photochromic dyes intothermoplastic materials, such as polycarbonate, involve either inclusionof organic photochromic dye throughout the thermoplastic material orimbibition of photochromic dye into a surface of the thermoplasticmaterial. Existing techniques, such as injection molding, for includingorganic photochromic dyes throughout thermoplastic materials, such aspolycarbonate, typically do not yield satisfactory results. It isbelieved that the unsatisfactory results occur for several reasons,including the relatively high temperatures required for satisfactoryinjection molding and including the relatively high glass transitiontemperatures of many thermoplastics, such as polycarbonate.

For example, naphthopyrans, spironaphthopyrans, and spirooxazines thatare co-melted with thermoplastics typically break down when exposed tothe relatively high temperatures present during injection molding. Thishas been found to be especially true when the thermoplastic material ispolycarbonate resin. As another example, polycarbonate, has a stiffmolecular structure that is reflected by the relatively high glasstransition temperature of polycarbonate. Therefore, even in the absenceof photochromic compound break down, the stiff molecular structure ofpolycarbonate would be expected to substantially inhibit full activationof the photochromic dye, since the photochromic dye must go through ageometric transformation in the polycarbonate to activate.

The present inventors conducted an experiment to examine thesephotochromic compound break down and activation inhibition phenomena.The experiment involved co-melting mixing equal concentrations of anorganic photochromic dye into polycarbonate resin and into celluloseacetate butyrate resin. Then, a sheet of the polycarbonate/photochromicdye mixture and a sheet of the cellulose acetate butyrate/photochromicdye mixture were cast. It was observed that the photochromic activity ofthe photochromic dye in the polycarbonate was approximately one halfthat of the photochromic activity of the photochromic dye in thecellulose acetate butyrate, under the same conditions of ultravioletlight exposure.

Imbibition of photochromic dyes into surfaces of thermoplasticmaterials, such as polycarbonate, also yields unsatisfactory results,which are again believed related, at least in part, to the relativelyhigh glass transition temperatures of many thermoplastics, such aspolycarbonate. For example, polycarbonate has a stiff molecularstructure, as reflected by the relatively high glass transitiontemperature of polycarbonate. Poor photochromic dye imbibition resultsobtained with polycarbonate are believed related to the stiff molecularstructure of polycarbonate. More specifically, it is thought that thestiff molecular structure substantially prevents the photochromic dyefrom penetrating into the polycarbonate.

Modification of the surface structure of polycarbonate by treatment witha solvent is said to improve imbibition of photochromic compounds intopolycarbonate. In particular, U.S. Pat. No. 5,268,231 to Knapp-Hayesdiscloses that cyclohexanone is one of the more effective solvents formodifying the polycarbonate surface structure to accept photochromiccompounds. However, the present inventors have completed experimentsfollowing the methods described in U.S. Pat. No. 5,268,231 and havefound that this method leaves the surface of the polycarbonate with arough, orange-peel type texture that is unacceptable for ophthalmiclenses. For example, the rough texture of the treated polycarbonatecauses irregular and unpredictable optical effects in the treatedpolycarbonate.

SUMMARY OF THE INVENTION

The present invention includes a method of making an optical elementthat includes a thermoplastic power portion. The method includeslaminating a first thermoplastic sheet to one side of a functional film,laminating a second thermoplastic sheet to a second side of thefunctional film, and affixing either the first thermoplastic sheet orthe second thermoplastic sheet to the power portion, with the other ofthe first or second thermoplastic sheets being open to atmosphere. Thepresent invention further includes a laminate for an optical element, amethod of making an optical element, a method of forming an opticalelement, a method of making a multi-focal lens, a method ofincorporating a desired property in an optical element, and a method ofcombining a power portion of an optical element and a functional portionof the optical element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of one embodiment of the optical element ofthe present invention.

FIG. 2 is a sectional view of one embodiment of the optical element ofthe present invention.

FIG. 3 is a schematic view of the functional portion of the presentinvention.

FIG. 4 is a sectional view of one embodiment of the optical element ofthe present invention.

FIG. 5 is a schematic view of an injection molding machine with a moldfor practicing the method of the present invention.

FIG. 6 is a schematic view of an injection molding machine with a moldfor practicing the method of the present invention, with the mold closedto form a mold cavity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An article of the present invention is generally indicated at 8 inFIG. 1. The article 8, which may take the form of an optical elementsuch as an optical lens 10, includes a primary part, such as a powerportion 12 and a secondary part, such as a functional portion 14. Thefunctional portion 14 and the power portion 12 are attached together.The functional portion 14 and the power portion 12 are preferablyintegrally connected to each other and, more preferably, are fusedtogether.

No method presently exists for making polarized,prescription-specification, polycarbonate lenses. The present inventionsolves this difficult challenge. For example, the functional portion 14of the present invention provides a convenient and systematic way ofcombining a polarizing element with a polycarbonate lens, whileretaining the ability to machine the polycarbonate lens to prescriptionspecifications. As best depicted in FIG. 3, the functional portion 14may include a functional member 20, such as a functional coating (notshown) or a functional film 21, that is attached to a first sheet 22.Optionally, the functional portion 14 may include a second sheet 24 suchthat the functional member 20 is sandwiched between the first sheet 22and the second sheet 24.

Though not depicted in FIG. 3, those skilled in the art will recognizethat the functional member 20 may be structured in a variety of ways,such as in composite or multi-layer fashion, in addition to thefunctional film 21. For example, the functional member 20 could bestructured to include film portions (not shown) that entrap and protectan operative substance, such as inorganic photochromic crystals. Asanother example, the functional member 20 could include multiplefunctional film portions (not shown) that are laminated together using aconventional technique.

A functional element, such as a polarizing element (not shown), may beincorporated into the functional member 20, such as the functional film21. The functional portion 14 that includes the polarizing element maythen be included in a mold, such as an injection mold, so that the film21 with the polarizing element is integrally molded as part of the lens10. Alternatively, a different functional element, such as aphotochromic, abrasion resistant, or tinting element, may beincorporated into the functional member 20, such as the film 21, andintegrally molded as part of the lens 10.

The functional portion 14 may incorporate one or more functionalproperties. Essentially, the functional portion 14 operates to putincorporated functional properties in working relation with the powerportion 12. Examples of some functional properties of interest includefiltering features, such as light polarization and photochromism.Additional examples of functional properties of interest includecosmetic properties, such as lens decor, indicia, tint and color. Stillfurther examples of functional properties include durability features,such as hardness, abrasion resistance, and chemical resistance.Preferably, the functional portion 14 includes a light polarizingcomponent or a photochromic component that functions as a filteringportion of the lens 10. Alternatively, or in addition, portions of thefunctional portion 14 may be tinted to function as a cosmetic portion ofthe lens 10.

The power portion 12 of the lens 10 may be contoured during initialformation to have an optical magnification characteristic that modifiesthe focal power of the lens 10. Alternatively, the power portion 12 maybe machined after initial formation to modify the focal power of thelens 10. The power portion 12 provides a substantial amount of theoptical power and magnification characteristics to the lens 10. Thefunctional portion 14 inherently affects the optical power andmagnification characteristics of the lens 10 since the functionalportion 14 contributes to the overall thickness of the lens 10.Preferably, however, the power portion 12 provides the majority of thelens 10 optical power and magnification characteristics. Apportioningthe majority of optical power and magnification to the power portion 12permits selection of power portion 12 material and power portion 12formation techniques that are optimum for superior lens 10 optical powerand magnification characteristics, without adversely affecting selectionof optimum functional portion 14 materials and formation techniques.

The power portion 12 of the lens 10 has both a rear surface 16 and afront surface 18. The functional portion 14 of the lens 10 may becoextensive with the front surface 18 of the power portion 12, as inFIG. 1. Alternatively, the functional portion 14 may overlap only aportion of the front surface 18 of the power portion 12, as in FIG. 2.Although FIGS. 1, 2, and 4 indicate definite lines of demarcationbetween the power portion 12 and the functional portion 14, suchdefinite lines do not necessarily exist when the power portion 12 andthe functional portion 14 are integrally connected. Rather, because ofintermolecular bonding, the demarcation line between the power portion12 and the functional portion 14 may be somewhat blurred when the powerportion 12 and the functional portion 14 are integrally connected.

The functional portion 14 may take the form of a plate 17, as in FIG. 3,that is separated from a functional laminate 19. The functional laminate19 includes the functional member 20, such as the functional film 21.The functional film 21 may include a base film (not shown) and afunctional medium (not shown) that is incorporated into or onto the basefilm. When the functional member 20 is other than the functional film21, the functional member 20 may include more than one base film (notshown). Alternatively, the functional film 21 may include the functionalmedium (not shown) and a base resin (not shown), with the functionalmedium and the base resin being homogeneously blended together prior toformation of functional film 21 from the medium/resin mixture. Besidesthe functional member 20, the functional laminate 19 includes the firstsheet 22 and, optionally, includes the second sheet 24. If the secondsheet 24 is included, the first and second sheets 22, 24 are located onopposing sides of the functional member 20.

The first sheet 22 may be attached to the functional member 20, such asthe functional film 21, by first adhesive 26, and the second sheet 24,if included, may be attached to the functional member 20 by secondadhesive 28. The first adhesive is typically not included when thefunctional member 20 is the functional coating (not shown). A firstcoating 30 may optionally be applied onto the first sheet 22 and asecond coating 32 may optionally be applied onto the second sheet 24, ifthe second sheet 24 is included. The second sheet 24 and the first andsecond coatings 30 and 32 are depicted with dashed lines to illustratethe optional nature of the second sheet 24 and the coatings 30, 32.

Alternatively, the functional portion 14 may consist of a functionalwafer (not shown) that includes the first sheet 22. In the functionalwafer, the functional member 20, and thus the functional film 21, mayconsist of either the second sheet 24, the second coating 32, or thesecond sheet 24 that is coated with the second coating 32. If thefunctional wafer includes the second sheet 24, the functional wafer mayoptionally also include either the first adhesive 26 or the secondadhesive 28 to attach the second sheet 24 to the first sheet 22. Also,the first sheet 22 may optionally include the first coating 30.

The functional portion 14 may be attached to the power portion 12 witheither the first sheet 22, the second sheet 24, the first coating 30, orthe second coating 32 in contact with the power portion 12. Preferably,the functional portion 14 is attached to the power portion 12 witheither the first sheet 22 or the second sheet 24 in contact (not shown)with the power portion 12, since the first and second coatings 30, 32tend to degrade adhesion of the functional portion 14 to the powerportion 12.

When the first sheet 22 or the first coating 30 is in contact with thepower portion 12, the second sheet 24 if included, may form an outsidesurface 34 of the lens 10 that is open to atmosphere and that protectsthe functional member 20 from marring and abrasion. The second coating32, if included, may substitute for the second sheet 24 as the outsidesurface 34. Alternatively, when the second sheet 24 or the secondcoating 32 is in contact with the power portion 12, the second sheet 24,if included, may form the outside surface 34 of the lens 10 that is opento atmosphere and that protects the functional member 20 from marringand abrasion. Also, the first coating 30, if included, may substitutefor the first sheet 22 as the outside surface 34. Furthermore, when thefunctional portion 14 takes the form of the functional wafer (notshown), the second sheet 24 or the second coating 32 may form theprotective outside surface 34.

The lens 10 may alternatively be characterized as having a front section(not shown), a functional section (not shown), and a rear section (notshown). In this characterization, the front section and the rear sectionare located on opposite sides of the functional section. Additionally,the functional member 20 may serve as the functional section and thepower portion 12 may serve as the rear section. Additionally, either thefirst sheet 22 or the second sheet 24, if included, may serve as thefront section.

The functional member 20, as indicated, preferably includes either thelight polarizing property or the photochromic property. When thefunctional member 20 includes the light polarizing property, the basefilm or resin is preferably of the polyvinyl alcohol-type, as describedin U.S. Pat. No. 5,051,309 to Kawaki, which is hereby incorporated byreference. Specific examples of suitable resins of either the base filmor the base resin include polyvinyl alcohol, polyvinylformal,polyvinylacetal, and saponified (ethylene/vinyl acetate) copolymer film,with polyvinyl alcohol being especially preferred.

When the functional member 20 includes the photochromic property, thebase film or base resin may include homo and copolymers of variousmaterials, such as cellulose acetate butyrate, poly(n-butylmethacrylate), poly(isobutyl methacrylate), poly(methyl methacrylate),poly(ethyl methacrylate), polyethylene, polypropylene,poly(acrylonitrile), poly(vinyl acetate), poly(vinyl chloride),poly(butadiene), and polyamide, that are formed from appropriatemonomers and pre-polymers using conventional polymerization technology.Cellulose acetate butyrate is the preferred material for the base filmor base resin since cellulose acetate butyrate readily incorporatesphotochromic dyes and since photochromic dyes activate and perform wellin cellulose acetate butyrate.

Examples of suitable dichroic substances, such as dichroic dyes, forimparting the light polarizing property to the base film or resin arelisted in U.S. Pat. No. 5,051,309 to Kawaki et al. Some examples ofsuitable dichroic substances include Chlorantine Fast Red (C.I. 28160),Chrysophenine (C.I. 24895), Sirius Yellow (C.I. 29000), Benzopurpurine(C.I. 23500), Direct Fast Red (C.I. 23630), Brilliant Blue 6B (C.I.24410), Chlorazol Black BH (C.I. 22590), Direct Blue 2B (C.I. 22610),Direct Sky Blue (C.I. 24400), Diamine Green (C.I. 30295), Congo Red(C.I. 22120), and Acid Black (C.I. 20470). It is to be understood thatthe dichroic substance incorporated in the base film or resin may beeither a single dichroic substance or a mixture that includes two ormore of the dichroic substances.

The functional member 20 may incorporate any organic or inorganicphotochromic substance or compound, such as photochromic substances orcompounds that are compatible with the base film or resin and that arecapable of imparting photochromic properties to the base film or resin.Also, the photochromic substances or compounds incorporated in thefunctional member 20 may be a mixture that includes two or moredifferent dichroic substances or compounds. Examples of organicphotochromic compounds suitable for imparting photochromic properties tothe functional member 20, such as the base film or resin, includenaphthopyrans, spironaphthopyrans, fulgides, fulgimides, salicylates,triazoles, oxazoles, and azobenzenes. Silver halide is one example of aninorganic photochromic compound that is suitable for impartingphotochromic properties to the functional member 20, such as the basefilm or resin.

The functional portion 14 substantially prevents the structure of thedichroic substance(s) or the photochromic compound(s) from being altereddue to placement of the dichroic substance(s) or the photochromiccompound(s) in working relation with the power portion 12. Preferably,the functional portion 14 prevents alteration of the structure ofdichroic substance(s) and photochromic compound(s) due to placement ofthe dichroic substance(s) or the photochromic compound(s) in workingrelation with the power portion 12. Additionally, the functional portion14 substantially prevents the light polarizing activity of the dichroicsubstance(s) and the photochromic activity of the photochromiccompound(s) from being altered due to placement of the dichroicsubstance(s) or the photochromic compound(s) in working relation withthe power portion 12. Preferably, the functional portion 14 preventsalteration of the light polarizing activity of the dichroic substance(s)and prevents any significant alteration of the photochromic activity ofthe photochromic compound(s) due to placement of the dichroicsubstance(s) or the photochromic compound(s) in working relation withthe power portion 12.

Examples of naphthopyran compounds suitable for imparting photochromicproperties to the functional member 20, such as the base film or resin,include novel naphthopyran compounds that may be represented by graphicformula I as follows: ##STR1## For purposes of the present application,including the description and the claims, it is to be understood thatgraphical formula I includes all structural isomers of the compoundsrepresented by graphical formula I.

A variety of substituents may be placed on the pyran portion and thenaphtho portion of the naphthopyran rings. For example, the positionsrepresented in graphic formula I by R₄, R₅, R₆, R₇, R₈, R₉, R₁₀, andR₁₁, respectively, may be filled with hydrogen; a stable organicradical, such as alky, alkoxy, unsubstituted or substituted phenyl,naphthyl, cycloalkyl, furyl, alkoyl, alkoyloxy, aroyl, aroyloxy; aheterocyclic group; halogen; a nitrogen-substituted group, such as aminoor nitro; or a nitrogen-substituted ring compound, such as morpholino,piperidino, or piperazino.

Also in graphic formula I, A is hydrogen, a substituted phenyl group, ora substituted naphthyl group, and B is hydrogen, a substituted phenylgroup, or a substituted naphthyl group, provided that at least one of Aand B is substituted phenyl or substituted naphthyl. The substituents ofany phenyl or naphthyl group or groups at A or B are selected from thefollowing: a stable organic radical, such as alkyl, alkoxy,unsubstituted or substituted phenyl, naphthyl, cycloalkyl, furyl,alkoyl, alkoyloxy, aroyl, aroyloxy; a heterocyclic group; halogen; anitrogen-substituted group, such as amino or nitro; and anitrogen-substituted ring compound, such as morpholino, piperidino, orpiperazino; provided that at least one substituent of at least onesubstituted phenyl or substituted naphthyl at either A or B is phenyl,naphthyl or furyl.

Preferred naphthopyran compounds for imparting photochromic propertiesto the functional member 20, such as the base film orresin, include3-(4-biphenylyl)-3-phenyl-8-methoxy-3H-naphtho 2,1b!pyran,3-(4-biphenylyl)-3-phenyl-3H-naphtho 2,1b!pyran, and3,3-di(4-biphenylyl)-8-methoxy-3H-naphtho- 2,1b!pyran.

Additional details about preparation and use of the novel naphthopyrancompounds represented by graphic formula I, including the preferrednaphthopyran compounds, may be obtained from U.S. patent applicationSer. No. 08/282,278 entitled "Photochromic Naphthopyran Compounds" andfiled on Jul. 28, 1994 in the name of Frank J. Hughes et al. asApplicants, which is hereby incorporated by reference.

Examples of spironaphthopyran compounds suitable for impartingphotochromic properties to the functional member 20, such as the basefilm or resin, include novel spironaphthopyran compounds that may berepresented by graphic formula II as follows: ##STR2## For purposes ofthe present application, including the description and the claims, it isto be understood that graphical formula II includes all structuralisomers of the compounds represented by graphical formula II.

A variety of substituents may be placed on the pyran and the naphthoportion of the spironaphthopyrans of the present invention. For example,the positions represented in graphic formula II by R₁, R₂, R₅, R₆, R₇,R₈, R₉, and R₁₀, respectively, may be filled with hydrogen; a stableorganic radical, such as alkyl, alkoxy, phenyl, naphthyl, cycloalkyl,furyl, alkoyl, alkoyloxy, aroyl, aroyloxy; a heterocyclic group; ahalogen; a nitrogen-substituted group, such as amino or nitro; or anitrogen-substituted ring compound, such as morpholino, piperidino, orpiperazino.

Also in graphic formula II, the position represented by A is filled by asubstituted divalent aromatic radical. The substituents of the divalentaromatic radical may be hydrogen or a stable organic radical such asalkyl, alkoxy, phenyl, naphthyl, cycloalkyl, furyl, alkoyl, alkoyloxy,aroyl, or aroyloxy. Additionally, the substituents of the substituteddivalent may also be substituted with alkyl, alkoxy, phenyl, naphthyl,cycloalkyl, furyl, alkoyl, alkoyloxy, aroyl, or aroyloxy.

Preferred spironaphthopyran compounds for imparting photochromicproperties to the functional member 20, such as the base film or resin,include 8-methoxyspiro(3H-naphtho 2,1-b!pyran-3,9'-fluorene),spiro(3H-naphtho 2,1-b!pyran-3,9'-fluorene), 8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-tetralone), 6',7'-dimethoxy-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-tetralone), 7'-methoxy-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-tetralone), 2',3'-diphenyl-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-tetralone), 2'-methyl-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-tetralone), 2'-methyl-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-indan), 2',3'-diphenyl-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-indene), 2',3'-diphenyl-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-tetralone), 2'-methyl-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-tetralone), 2'-methyl-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-indan), and 2',3'-diphenyl-8-methoxyspiro(3H-naphtho2,1-b!pyran-3,1'-indene).

Additional details about preparation and use of the novel naphthopyrancompounds represented by graphic formula II, including the preferrednaphthopyran compounds, may be obtained from U.S. patent applicationSer. No. 08/331,281 entitled "Photochromic Spironaphthopyran Compounds"and filed on Oct. 28, 1994 in the name of Frank J. Hughes et al. asApplicants, which is hereby incorporated by reference.

The first sheet 22 and the second sheet 24 should be compatible with thepower portion 12, the functional member 20, the first and secondadhesives 26, 28, and, if included, the first and second coatings 30,32. In this context, compatibility means that the first sheet 22 or thesecond sheet 24, as appropriate, is capable of either strongly adheringto or strongly fusing with the material of the power portion 12.Additionally, compatibility means that the material of the first sheet22 and of the second sheet 24 is incapable of undesirably reacting withother lens 10 components to degrade the power portion 12, the functionalmember 20, the first adhesive 22, the second adhesive 24, the firstcoating 30 (if included), the second coating 32 (if included), orfunctional media, such as photochromic or polarizing compoundsincorporated in the functional member 20.

Furthermore, the power portion 12 and the one of the first sheet 22 andthe second sheet 24 that is attached to the power portion 12 maygenerally be made of any resinous material. Thus, the first sheet 22 andthe second sheet 24 may each be made of different materials, such asdifferent thermoplastic resins. Additionally, either or both of thesheets 22, 24 may be made of a different material than the power portion12 is made of. Preferably, the power portion 12 and the one of the firstsheet 22 and the second sheet 24 that is attached to the power portion12 are each made of any of a variety thermoplastic resins, includinghomopolymers and copolymers of polycarbonate, amorphous polyolefin,polystyrene, and acrylic compounds, so long as the aforementionedmaterial compatibility requirement is met, to permit fusion of the powerportion 12 to the first sheet 22 or second sheet 24. More preferably,the power portion 12 and the one of the first sheet 22 and the secondsheet 24 that is attached to the power portion 12 are each made of thesame thermoplastic resin to further enhance fusion of the power portion12 to the first sheet 22 or second sheet 24.

Materials suitable for use as the first adhesive 26 and the secondadhesive 28 must have good optical properties, including high opticaltransparencies, no yellowing upon exposure to sunlight, an ability toflex during injection molding without becoming crazed, minimal shrinkageduring curing, and must meet the aforementioned material compatibilityrequirement. Some examples of suitable materials for the first adhesive26 and the second adhesive 28 include acrylic-type, epoxy-type andurethane-type adhesives, such as Loctite® FMD-207, Loctite® FMD-338,Loctite® FMD-436, and Loctite® 3311, each available from LoctiteCorporation of Hartford, Conn.; Norland Optical Adhesive Type 68available from Norland Products Inc. of New Brunswick, N.J.; and SummersLaboratories Type SK-9 available from Summers Laboratories, Inc. ofCollegeville, Pa. The materials used for the first adhesive 26 and thesecond adhesive 28 may be curable by thermal treatment or by treatmentwith ultraviolet light.

The first coating 30 and the second coating 32 may be formed of anymaterial(s) suitable for providing hardness, abrasion resistance, and/orchemical resistance to the functional portion 14, so long as theaforementioned material compatibility requirement is met. Some examplesof suitable coating materials include hard acrylic coatings and hardpolysiloxane compounds. Preferably, the one of the sheets 22, 24 that isin contact with the power portion 12 does not include the respectivecoating 30, 32, since it has been found that coating of the one of thesheets 22, 24 that is in contact with the power portion 12 tends todecrease bonding of the functional portion 14 to the power portion 12.

One benefit of the lens 10 of the present invention is that an overallcenter thickness A of the lens 10, referring to FIG. 1, measured alonglongitudinal axis Z of the lens 10 may be minimized to decrease theweight of the lens 10. For example, in accordance with the presentinvention, a center thickness B of the power portion 12 preferablyranges from about 0.9 mm to about 20.0 mm and more preferably rangesfrom about 1.0 mm to about 9.0 mm. Similarly, though a center thicknessC of the functional portion 14 may be any thickness that is adequate toobtain the desired functional effect, such as the light polarizingeffect or the photochromic effect, in the lens 10, the center thicknessC of the functional portion 14 preferably ranges from about 0.2 mm toabout 2 mm and more preferably ranges from about 0.3 mm to about 0.7 mm.Though the center thicknesses B and C of the power portion 12 and thefunctional portion 14 are depicted in FIG. 1 as being offset from theaxis Z of the lens, it is to be understood that the center thicknesses Band C of the power portion 12 and the functional portion 14,respectively, are each measured along the axis Z. Finally, the centerthickness A of the lens 10 preferably ranges from about 1.5 mm to about22.0 mm and more preferably ranges from about 1.6 mm to about 10.0 mm.

The preferred and more preferred ranges of thickness of the functionalfilm 21, the first and second sheets 22, 24, the first and secondadhesives 26, 28, and the first and second coatings 30, 32, if included,are presented in Table 1 below:

                  TABLE 1                                                         ______________________________________                                                    PREFERRED      MORE PREFERRED                                     ______________________________________                                        Functional Film 21                                                                        from about 0.0005 mm                                                                         from about 0.0007 mm                                           to about 0.002 mm                                                                            to about 0.001 mm                                  First Sheet 22                                                                            from about 0.2 mm                                                                            from about 0.3 mm                                              to about 1.0 mm                                                                              to about 0.35 mm                                   Second Sheet 24                                                                           from about 0.2 mm                                                                            from about 0.3 mm                                  (optional)  to about 1.0 mm                                                                              to about 0.35 mm                                   First Adhesive 26                                                                         from about 0.0005 mm                                                                         from about 0.0007 mm                                           to about 0.002 mm                                                                            to about 0.001 mm                                  Second Adhesive 28                                                                        from about 0.0005 mm                                                                         from about 0.0007 mm                                           to about 0.002 mm                                                                            to about 0.001 mm                                  First Coating 30                                                                          from about 0.0003 mm                                                                         from about 0.0004 mm                               (optional)  to about 0.001 mm                                                                            to about 0.006 mm                                  Second Coating 32                                                                         from about 0.0003 mm                                                                         from about 0.0004 mm                               (optional)  to about 0.001 mm                                                                            to about 0.006 mm                                  ______________________________________                                    

As noted, when the functional portion 14 takes the form of thefunctional wafer (not shown), the functional film 21 may consist ofeither the second sheet 24, the second coating 32, or the second sheet24 that is coated with the second coating 32. Thus, when the functionalportion 14 takes the form of the functional wafer (not shown), it shouldbe readily understood that consequent changes in the thickness of thefunctional film 21 will result.

The lens 10 may be either a single vision lens, a progressivemulti-focal lens, an aspheric lens, an aspheric multi-focal lens, or astepped multi-focal lens. Single vision lenses, which may take the formof the lens 10, have essentially the same focal power at any point onthe outside surface 34 of the lens 10 when objects (not shown) locatedin front of the functional portion 14 of the lens 10 are viewed throughthe lens 10 from a select point X located behind the lens 10 and on theaxis Z. The outside surface 34 should be substantially smooth, and ispreferably very smooth, to help minimize generation of any irregular,unpredictable optical effects in the lens 10.

For the progressive multi-focal lens, which may also take the form ofthe lens 10, the focal power of the lens 10 changes in continuousincrements when objects located in front of the outside surface 34 areviewed from the select point X through different points of the outsidesurface 34. For the progressive multi-focal lens, the focal power of thelens 10, when viewing objects from point X, changes in continuousincrements when moving about the outside surface 34, in part due to thesmooth continuous nature of the outside surface 34 of the lens 10 thatis progressive multi-focal. When the lens 10 is progressive multi-focal,the front surface 18 and the outside surface 34 are aspherically shaped.Additionally, when objects are viewed from point X through the lens 10that is progressive multi-focal, lines are not seen when moving betweenpoints about the surface 34 that have different focal powers.

When the lens 10 is a stepped multi-focal lens, such as the lens 10depicted in FIG. 4, the front surface 18 of the power portion 12 isdiscontinuous. For example, the lens 10 of FIG. 4 is a stepped bi-focallens in which the front surface 18 is divided into a main focal surface36 and a secondary focal surface 38. The main focal surface 36 and thesecondary focal surface 38 cooperate to define a stepped surface 40 thatdisrupts smooth transition between the main focal surface 36 and thesecondary focal surface 38. As depicted in FIG. 4, the secondary focalsurface 38 may be elevated, at least in part, relative to the main focalsurface 36. Alternatively, though not depicted in FIG. 4, it is to beunderstood that the main focal surface 36 may be elevated, at least inpart, relative to the secondary focal surface 38. Furthermore, it is tobe understood that when the lens 10 is stepped multi-focal, the frontsurface 18 may be divided into more than two discontinuous surfaces,rather than only the two discontinuous surfaces, namely the main focalsurface 36 and the secondary focal surface 38, as depicted in FIG. 4.

When the lens 10 is multi-focal, the lens 10 may be either progressivemulti-focal, aspheric multi-focal, or stepped multi-focal. The costs ofobtaining the progressive and the aspheric multi-focal lenses aresomewhat comparable to the cost of obtaining the stepped multi-focallenses. Manufacture of stepped multi-focal lenses requires somewhat lessexpensive and somewhat less complicated tooling than does manufacture ofprogressive multi-focal lenses or manufacture of aspheric multi-focallenses. On the other hand, actual manufacturing costs for steppedmulti-focal lenses are somewhat higher that are manufacturing costs forprogressive or aspheric multi-focal lenses.

Nonetheless, the lens 10 is preferably progressive multi-focal, ratherthan stepped multi-focal, since shaping of the functional portion 14 tomatch the shape of the front surface 18 of the power portion 12 iseasier for the progressive multi-focal lens than for the steppedmulti-focal lens. Furthermore, progressive multi-focal lenses aregenerally perceived by consumers to be a more sophisticated andcosmetically appealing lens than stepped multi-focal lenses.Additionally, the lens 10 is preferably progressive multi-focal, ratherthan aspheric multi-focal, since progressive multi-focal lenses aregenerally perceived by consumers to be a more sophisticated andcosmetically appealing lens than aspheric multi-focal lenses.

The lens 10, as in FIGS. 1, 2, and 4, may be either a finished lens or asemi-finished lens. When the lens 10 is the finished lens, the focalpower or focal power range of the lens is set during manufacture of thelens 10 and no further processing of the lens 10 is required to set thefocal power or focal power range. When the lens 10 is semi-finished,additional processing after initial manufacture of the lens 10, such asgrinding of a rear surface 42 of the lens 10, is needed to set the focalpower or focal power range of the lens 10. If the lens 10 is finished,the rear surface 42 may include a coating (not shown) to enhance thehardness and abrasion resistance of the rear surface 42 of the lens. Ifthe lens 10 is semi-finished, the coating need only be applied to theoutside surface 34 of the lens 10, since the coating on the rear surface42 of the lens 10 may be damaged or removed during further processing ofthe semi-finished lens. However, even if the lens 10 is semi-finished,the rear surface 42 may include the coating (not shown) to simplify orreduce the cost of manufacturing the semi-finished lens.

The method of making the lens 10 generally involves three distinctsteps. First, the functional member 20, such as the functional coating(not shown) or the functional film 21, is prepared. Next, the functionalportion 14 is prepared. Finally, the lens 10 is made by attaching thefunctional portion 14 to the power portion 12.

It is to be understood that functional properties in addition topolarization or photochromism, such as tint, color, hardness, abrasionresistance, and chemical resistance, decor, and indicia may beincorporated in the functional member 20, such as functional coating(not shown) or the functional film 21, using conventional techniques.However, the functional film 21 preferably incorporates either the lightpolarization property or the photochromic property. Additionally, any ofthe sheets 22, 24 or the coatings 30, 32 may impart durabilitycharacteristics, such as hardness, abrasion resistance, and chemicalresistance, to the lens 10 and especially to the outside surface 34 ofthe lens.

The dichroic compound(s) may be incorporated into the base film to makethe functional film 21 with the polarizing property using any suitableprocedure. For example, the base film (not shown) may be immersed in anaqueous solution of dichroic substance at a temperature ranging fromabout 10° C. to about 50° C. to effect absorption of the dichroicsubstance on the base film. Next, the base film is stretched in onedirection to a dimension ranging about 21/2 times to about 8 times theunstretched dimension of the base film in a water solution with atemperature ranging from about 10° C. to about 80° C. The water solutionshould contain a dissolved additive, such as a metal ion or boric acid,to effect adsorption and orientation of the dichroic substance(s) ontothe base film.

The organic photochromic compound(s) may be incorporated into the basefilm to make the functional film 21 having the photochromic propertyusing any suitable procedure. As an example, in one suitable procedureuseful for the preferred naphthopyrans and spironaphthopyrans thephotochromic compound(s) are dissolved in a suitable solvent. Examplesof suitable solvents include butyl acetate; hexane; cyclohexane; variousalcohols, including ethanol and methanol; and various ketones; such ascyclohexanone and methyl ethyl ketone. Next, a photochromiccompound/resin/solvent mixture is made by adding the photochromiccompound/solvent solution to the molten monomer or molten pre-polymer ofthe homopolymer or copolymer selected for the base film. A suitableultraviolet stabilizing compound may be incorporated into thephotochromic compound/resin/solvent mixture to help stabilize thephotochromic compound(s) against activation fatigue.

In a second suitable alternative for the preferred naphthopyrans andspironaphthopyrans, the photochromic compound(s) and the homopolymer orcopolymer resin selected for the base film are first mixed together. Thesolvent is then added to the photochromic compound/resin mixture, andthe photochromic compound/resin/solvent mixture is heated to melt and/ordissolve the photochromic compound(s) and resin in the solvent andhomogeneously mix all components of the mixture.

The mixture of photochromic compound(s), solvent, and monomer orpre-polymer, however created, may be formed into a film or sheet by asuitable extrusion or casting method. Preferably, the mixture is cast ona flat surface using a conventional thermoset plastic casting technique.Upon evaporation of the solvent from the cast film or sheet, thefunctional film 21 having the photochromic property remains.

The inorganic photochromic compound(s) may be incorporated into thefunctional member 20, such as the functional film 21, having thephotochromic property using any suitable procedure. As an example, theinorganic photochromic compound(s) may be any suitable potentiallyphotochromic glass that is treated and ground to make photochromic glassparticles in accordance with U.S. Pat. No. 4,622,184 to Barnhart et. al,which is hereby incorporated by reference. The photochromic glassparticles may be blended with the base resin, as specified in U.S. Pat.No. 4,622,184, and then may be formed into the functional film 21 aconventional method, such as a suitable extrusion or casting method.

As another example, the inorganic photochromic compound(s), such assilver halide particles, may be co-deposited along with a monomer on asubstrate, such as the base film, in accordance with U.S. Pat. No.4,596,673 to Beale, which is hereby incorporated by reference. Themonomer polymerizes as a result of the co-deposition to secure thesilver halide to the base film. Monomers that are suitable for use inpracticing the method of U.S. Pat. No. 4,596,673 includehexamethyldisiloxane, hexamethyldisilizane, vinyl trimethylsiloxane,tetramethyldisiloxane, and vinyl trimethoxysilane. The functional film21 that incorporates the inorganic photochromic compound(s), such as thesilver halide particles, remains after the monomer polymerizes.

As an additional example, the base resin may be prepared by combining(1) an unsaturated polyester resin produced by esterification of apolybasic unsaturated organic acid with a polyhydric alcohol and (2) apolar vinyl monomer of the type that forms polar solvent soluble plasticwhen homopolymerized, in accordance with U.S. Pat. No. 4,110,244 toHovey, which is hereby incorporated by reference. One or moreunsaturated vinyl monomers may, if desired, be blended with theunsaturated polyester resin before the polyester resin is combined withthe polar vinyl monomer. The mixture of the unsaturated polyester resin,either with or without the unsaturated vinyl monomer(s), and the polarvinyl monomer may be polymerized and cast in accordance with U.S. Pat.No. 4,110,244 to form the base film. The base film is then immersed inionic solutions in accordance with U.S. Pat. No. 4,110,244 to form thefunctional film 21 that incorporates the inorganic photochromiccompound(s), such as silver halide.

As another example, the inorganic photochromic compound(s), such assilver halide crystals, may be coated with an inorganic material to makecoated photochromic material, in accordance with U.S. Pat. No. 4,046,586to Uhlmann et al., which is hereby incorporated by reference. The coatedphotochromic material may then be blended, as indicated in the Uhlmannpatent, with a solution of the base resin in a suitable solvent. Thefunctional film 21 may then be prepared by casting the mixture of thebase resin, the solvent, and the coated photochromic material, using aconventional casting technique.

As yet another example, the inorganic photochromic compound(s), such assilver halide crystals, may be incorporated into a photochromic plasticmaterial, as explained in U.S. Pat. No. 4,049,567 to Chu et al., whichis hereby incorporated by reference. The photochromic plastic materialmay then be sandwiched between two sheets of the base film and sealedwith epoxy resin, in accordance with the Chu patent, to form thefunctional member 20. This is an example of how the functional member 20may be structured other than as the functional film 21.

After the functional member 20, such as the functional film 21, isprepared, the functional portion 14 may be made by laminating the firstsheet 22 and, if desired, the second sheet 24 to the functional member20 using the first adhesive 26 and the second adhesive 28, respectively.Any conventional adhesive-based lamination technique, such as rolling toapply suitable pressure, may be relied upon to laminate the sheets 22,24, to the functional member 20. The coating 30, if included, may beapplied to the first sheet 22 either before or after lamination of thesheet 22 to the functional member 20. Similarly, if the second sheet 24is included, the coating 32, if included, may be applied to the secondsheet 24 either before or after lamination of the sheet 24 to thefunctional member 20.

Alternatively, when the functional member 20 is the functional coating(not shown), the functional portion 14 may be prepared by applying thefunctional coating onto the first sheet 22 using any suitable procedure,such as spraying, brushing, or powder application. Examples of materialsthat are suitable for forming the functional coating include thosematerials that are suitable for providing functional properties, such ashardness, abrasion resistance, and/or chemical resistance, to thefunctional portion 14, so long as the aforementioned materialcompatibility requirement is met. Some examples of suitable materialsfor the functional coating include hard acrylic coatings and hardpolysiloxane compounds.

When the functional coating (not shown) is included, the first adhesive26 is optional since the functional coating may be applied directly ontothe first sheet 22. typically provides the outside surface 34 of thelens 10. Also, the second adhesive 28, the second sheet 24, and thesecond coating 32 are optional when the functional member 20 is thefunctional coating since the functional coating may be used to form theoutside surface 34 of the lens 10. Furthermore, the functional coatingmay be selected to provide the outside surface 34 with desirablefunctional properties, such as hardness, abrasion resistance, and/orchemical resistance.

In one preferred embodiment, the functional film 21 that incorporatesthe polarizing property is a purchased item known as POLA SHEET. POLASHEET may be obtained by contacting Yushi Seihin Co. in Tokyo, Japan. Itis believed that the functional film 21 having the photochromic propertyis not available as a purchased item. Therefore, it is necessary to makethe functional film 21 having the photochromic property using the methodof the present invention.

Alternatively, when the functional portion 14 takes the form of thefunctional wafer (not shown), the functional portion 14 may be preparedby laminating the second sheet 24 to the first sheet 22 using the firstadhesive 26 or the second adhesive 28. Any conventional adhesive-basedlamination technique may be relied upon to laminate the sheets 22, 24,together. The coatings 30, 32, if included, may be applied to the firstsheet 22 and the second sheet 24, respectively, either before or afterlamination of the sheets 22, 24. When the functional wafer (not shown)does not include the second sheet 24, the second coating 32 may beapplied to the first sheet 22 using any conventional coating applicationtechnique.

The power portion 12 and the functional portion 14 may be combined tomake the lens 10 using any conventional technique, such as laminatebonding, injection molding, compression molding, orinjection-compression molding (sometimes called "coining"). No matterthe method used to join the power and functional portions 12, 14, theplate 17 must be separated from the functional laminate 19 andconfigured to the size and pattern the plate 17 will have when includedin the lens 10. The plate 17 may be separated from the laminate 19 usingany conventional technique. Other than in the Examples, all subsequentcomments about plate 17 apply with equal force to the functional wafer.Some examples of potential plate 17 sizes and shapes are depicted inFIGS. 1 and 2. The plate 17 may be pre-shaped either before beingincorporated into the lens 10 or, alternatively, the plate 17 may beshaped while being incorporated into the lens 10.

The plate 17 may be pre-shaped using any suitable laminate shapingprocess. One example of a suitable process entails heating the plate 17to a suitable temperature. Simultaneous with or subsequent to theheating, positive pressure is applied to the plate 17 using a suitabledevice to shape the plate 17 and match the shape of the front surface 18of the power portion 12. Once the plate 17 is appropriately shaped, theplate 17 is cooled to room temperature and the positive pressure isreleased.

In accordance with the method of the present invention, the power andfunctional portions 12, 14 may be joined to make the lens 10 using amolding machine 100, as in FIG. 5, that includes a plurality of moldsurfaces 102. When the molding machine 100 is closed, as in FIG. 6, themold surfaces 102 define a plurality of mold cavities 104. Though twomold cavities 104 are depicted in FIG. 6, it is to be understood thatthe molding machine 100 may include only one of the mold cavities 104and may also include more than two of the cavities 104.

The molding machine 100 is preferably a reciprocating screw injectionmolding machine. The molding machine 100, referring back to FIG. 5,includes an injection portion 106 and a clamping portion 108. Theinjection portion 106 includes a barrel 110 that contains areciprocating screw (not shown). The injection portion 106 also includesa hopper 112 that directs pelletized thermoplastic resin (not shown) tothe screw. The injection portion 106 further includes a plurality ofheater bands 114 arranged about the barrel 110 to melt the thermoplasticresin. Additionally, the injection portion 106 includes a hydraulicpower unit 116 that rotates and reciprocates the screw.

The clamping portion 108 includes a mold portion 118 and a drive portion120 that opens and closes the mold portion 118. The mold portion 118includes a fixed mold half 122 that is in fixed association with theinjection portion 106. The mold portion 118 also includes a movable moldhalf 124 that is in mateable association with the fixed mold half 122.Together, referring to FIG. 6, the mold halves 122, 124 cooperativelydefine the mold cavities 104. The mold surfaces 102 of each mold cavity104 may be classified into three types of molding surfaces, namely, aconvex surface 126, a concave surface 128, and radial surfaces 130. Theconvex surface 126 of the mold cavity 104 defines the outside surface 34of the lens 10. The convex surface 126 may be configured to match anyshape of the outside surface 34 of the lens 10, including thediscontinuous shape, as in FIG. 4, of the outside surface 34. Similarly,the concave surface 128 of the mold cavity 104 defines the rear surface42 of the lens 10.

The radial surfaces 130 of the mold cavity 104 define a perimeter 44 ofthe lens 10. The radial surfaces 130 may be entirely defined in themovable mold half 124, as depicted in FIG. 5. Alternatively, though notdepicted in the Figures, the radial surfaces 130 may be entirely definedin the fixed mold half 122 or may be partially defined in the fixed moldhalf 122 and partially defined in the movable mold half 124.

The fixed mold half 122 has a sprue 132 that is in fluid communicationwith the injection unit 106. Additionally, opposing surfaces 134 of thefixed mold half 122 and the movable mold half 124 cooperatively definebranches 136, as depicted in FIG. 6, which place the injection unit 106and the sprue 132 in fluid communication with each mold cavity 104. Themold portion 118 additionally includes a plurality of cooling lines 138oriented within the mold halves 122, 124 to cool molten thermoplasticresin after injection of the resin into the mold cavity 104 is complete.

The movable mold half 124 preferably includes a fixed mold plate 146 anda movable mold plate 148. The mold half 124 also includes a plurality ofsleeves 150 that are in substantial registry with radial surfaces 130 ofthe mold cavities 104. The mold half 124 further includes a plurality ofpistons 152 that are slideably received within the sleeves 150 and arefixedly attached to the mold plate 148 at ends 154. Ends 156 of thepistons 152 form the convex surfaces 126 of the mold cavities 104.

The drive portion 120 of the clamping unit 108 includes a hydraulic ram158 that is in working relationship with the movable mold half 124. Thedrive portion 120 further includes a hydraulic power unit 160 thatdrives the hydraulic ram 158 and places the movable mold portion 124either in an open condition 162, as in FIG. 5, or in a closed position164, as in FIG. 6.

The movable plate 148, and thus the pistons 152, are in working relationwith the hydraulic ram 158. Movement of the plate 148 and the pistons152 is timed so that the pistons 152 move in the direction of arrow D,as best depicted in FIG. 5, after molding of the lenses 10 is completeand as the mold halves 122, 124 are separated. Movement of the pistons152 in direction D ejects the lenses 10 from the mold cavities 104 bysubstantially even application of pressure over the rear surface 42 ofeach lens 10. Conversely, movement of the plate 148 and the pistons 152is timed so that the pistons 152 move in the direction of arrow E toorient the surfaces 126, 128, 130 for molding following ejection of thelenses 10.

The clamping unit 108, as best depicted in FIG. 6, includes a pluralityof tie bars 166 that help maintain the movable mold half 124 in mateablealignment with the fixed mold half 122. Also, the fixed mold half 122includes cylindrical female guides 168, and the movable mold half 124includes cylindrical male members 170 that slidably engage respectivecylindrical female guides 168. The guides 168 and members 170 helpmaintain proper alignment of the fixed and movable mold halves 122, 124relative to each other.

In one embodiment, the mold halves 122, 124 are made of a low carbonplastic mold steel, such as Series P20 stainless steel tool steel. Themolding machine 100 may be any suitable injection molding machine, suchas a Vista injection molding machine which is available from CincinnatiMilacron of Batavia, Ohio.

Prior to molding the lens 10 in the molding machine 100, the plate 17that makes up the functional portion 14 is placed against a recess 172of the mold plate 146, as best depicted in FIG. 5, before the moldhalves 122, 124 are closed. The recess 172 may be defined by a notch(not shown) in the convex surface proximate the intersection of theconvex surface 126 and the radial surface 130, as best depicted in FIG.6. Alternatively, when any portion of the radial surface 130 is definedin the fixed mold half 122, the recess 172 may be defined by theintersection of the convex surface 126 and the radial surface 130. Whenthe plate 17 has a different size or shape than the front surface 18, asin FIG. 2, the convex surface 126, as in FIG. 5, may be notched (notshown) accordingly to reposition the recess 172 elsewhere in the convexsurface 126 to accommodate the different size or shape of the frontsurface 18.

As noted, the plate 17 may be pre-shaped to match the shape of the frontsurface 18 of the power portion 12. Alternatively, the molding machine100 may be configured with a vacuum source 174 and associated vacuumlines that are in communication with the convex surface 126 of eachcavity 104, as in FIG. 5. Using the vacuum source 174, each plate 17 maybe placed against respective recesses 172 and pulled into communicationwith respective convex surfaces 126 without pre-shaping the plates 17prior to placement in the machine 100.

No matter whether the plates 17 are pre-shaped outside the mold cavities104 or are shaped in the mold cavities 104, each plate 17 should beplaced in the respective mold cavity 104 so that a pneumatic seal (notshown), a mechanical seal (not shown), or a combinationpneumatic/mechanical seal (not shown) is created between each plate 17and the respective convex surface 126 of the mold half 122. Themechanical seal relates to the plates 17 that are pre-shaped. To obtainthe mechanical seal, the plates 17 must be properly sized to take intoaccount expansion of the metal used to make the mold halves 122, 124 sothat the plates 17 remain snug and secure within the recesses 172 whenmolten resin is injected into the mold cavities 104. The pneumatic sealrelates to the plates 17 that are shaped by the vacuum source 174 andmay also relate to the plates 17 that are pre-shaped. The pneumatic sealmay be created by applying sufficient vacuum to maintain the plates 17snugly in registry against the respective convex surfaces 126 whilemolten resin is injected into the mold cavities 104.

Sealing between plates 17 and respective convex surfaces 126 isnecessary to prevent molten thermoplastic resin that is injected intothe mold cavities 104 from flowing between the plates 17 and respectiveconvex surfaces 126. Intrusion of the molten resin between the plates 17and the convex surfaces 126 would be expected to undesireably create oneor more optical or cosmetic problems, such as delamination of thefunctional film from the sheet 22, 24, burning of the plate 17 or thefilm 21, stress points within the plate 17, warpage of the plate 17, andflow lines on the outside surface 34 of the lens 10.

After placement of the plates 17 against the recesses 172, the moldingmachine 100 is closed to form the mold cavities 104, as in FIG. 6. Thethermoplastic resin selected for the power portion 12 is then injectedinto the cavities 104 in the molten state to fill that portion (notshown) of the cavities 104 not occupied by the plates 17 and form thepower portion 12 of each lens 10. Additionally, in each cavity 104, theinjected resin comes into abutting contact with the plate 17 located inthe cavity 104. The temperature of the injected resin causes the powerportion 12 formed by the injected resin to fuse with the functionalportion 14 at the one of the sheets 22, 24 that is preferably orientedagainst the front surface 18 of the power portion 12. The heat presentin each cavity 104 is preferably sufficient to cause the power portion12 and the functional portion 14 to fuse together by welding into apermanent bond. After the injected resin solidifies, the cavity 104 maybe opened by moving the molding halves 122, 124 away from each other, asin FIG. 5. Preferably, the lens 10 is then ejected from the moldingmachine 100 by movement of the appropriate piston 152 in direction D.

Formation of the power portion 12 in the molding machine 100 highlightsanother important advantage of the present invention, namely, theequalizing effect that the power portion 12 exerts within the lens 10upon any non-uniformities in the thickness of the functional portion 14.Though it is preferred that the functional portion 14 be substantiallyuniform in thickness, some variation in thickness of the functionalportion 14 is permissible. Thickness variation in the functional portion14 is permissible because mold cavity 104 is uniform in thickness. Thus,injection of resin into the mold cavity 104 compensates for anynon-uniformities in thickness of the functional portion 14 by varyingthe thickness of the power portion 12 accordingly.

After being removed from the machine 100, each lens 10 may be coatedwith a suitable coating, such as an acrylic or a polysiloxane coatingcomposition, to provide a hard surface on the lens 10. Coating may beaccomplished using conventional techniques such as dipping, spraying, orspin-coating. As already noted, if lens 10 is finished after applicationof the coating, the coating may be applied to the outside surface 34 andthe rear surface 42 of the lens 10. If the lens 10 is semi-finished, thecoating need only be applied to the outside surface 34 of the lens 10,since the coating on the rear surface 42 may be damaged or removedduring further processing of the semi-finished lens. Alternatively, thecoating may be applied to all surfaces of the semi-finished lens,including the outside surface 34 and the rear surface 42 to simplify orreduce the cost of manufacturing the semi-finished lens.

A number of advantages are realized when the method of the presentinvention is used to make the lens 10. For example, functionalproperties are readily incorporated into the lens 10 without alteringthe substantially smooth nature, and preferably the very smooth nature,of the outside surface 34. Thus, undesirable and unpredictable opticaleffects that would otherwise be expected to occur in the lens 10, if theoutside surface 34 were other than smooth in nature, are greatlyminimized or eliminated altogether when the lens 10 of the presentinvention is used.

Also in accordance with the present method, the lens 10 may be finished,as opposed to semi-finished, with the power portion 12 being contouredto modify the focal power of the lens 10. Alternatively, the lens 10 maybe semi-finished so that the power portion is capable of being machined,at some time following manufacture, to modify the focal power of thelens 10.

Additionally, it has been discovered that the functional portion 14substantially beneficially prevents the structural alteration ofdichroic substances and photochromic compounds due to placement of thedichroic substances or the photochromic compounds in working relationwith the power portion 12. Furthermore, it has been discovered that thefunctional portion 14 substantially prevents the alteration of the lightpolarizing activity of dichroic substances and alteration of thephotochromic activity of photochromic compounds due to placement of thedichroic substances and the photochromic compounds, respectively, inworking relation with the power portion 12.

The method of the present invention provides a systematic approach forincorporating a wide variety of functional properties into the lens 10simply by modifying the functional portion 14. Also, the method of thepresent invention provides a systematic method for incorporatingfunctional properties into optical elements, such as the lens 10, evenas new materials supplant presently favored materials, such aspolycarbonate, in lens 10 manufacture. When a new material is developed,the material used to make the first sheet 22 and the second sheet 24 maybe modified to maintain compatibility between the new material and thematerials used in the functional portion 14, including the materials ofthe first and second sheets 22, 24.

It should also be understood that the functional portion 14 may beattached to any surface of a new or existing lens (not shown) using anyconventional technique, such as adhesive attachment or laminate bonding.In this way, functional properties may be imparted to new lenses thatinitially lack the properties. Also, functional properties may beimparted to existing lenses, instead of discarding the existing lensesand manufacturing new lenses that include the functional properties.Additionally, suitable solvents may be applied to remove the functionalportion 14 from the existing lens (not shown) so that a different one ofthe functional portions may be applied to the existing lens. This optionfacilitates changing the functional properties of the existing lens whenthe need for particular functional properties changes.

The present invention is more particularly described in the followingexamples which are intended as illustrations only since numerousmodifications and variations within the scope of the general formulationwill be apparent to those skilled in the art.

EXAMPLES Examples 1-4

Examples 1-4 demonstrates formation of the lens 10 with the polarizingproperty incorporated in the functional portion 14. Additionally, thelens 10 formed in Examples 1-4 each have different physical dimensionsand different focal powers.

More particularly, in Examples 1-4, the functional laminate 19 includedthe functional film 21, the first and second sheets 22, 24, and thefirst and second adhesives 26, 28. The functional laminate 19 alsoincluded the second coating 32, but did not include the first coating30. The functional laminate 19 included the light polarizing propertyand consisted of POLA SHEET obtained through Yushi Seihin Co. of Tokyo,Japan. The base film of the functional film 21 was made of polyvinylalcohol, and the first and second sheets 22, 24 were made ofpolycarbonate. The film 21 was about 0.003 mm thick and the first andsecond sheets 22, 24 were each about 0.3 mm thick. The adhesives 26, 28,which were each about 0.003 mm thick, were ordinary acrylic-type,epoxy-type, or urethane-type adhesives. The coating 32, which was about0.003 mm thick, was a hard polysiloxane coating.

For each lens 10 of examples 1-4, the plate 17 was cut from thefunctional laminate to make the functional portion 14. The plate 17 wasgenerally round in shape and had substantially the same dimensions asthe surface 18 of the power portion 12 to be made. The plate 17, whichwas not pre-shaped, was placed within the recesses 172 so that thesecond sheet 24 faced the convex surface 126. The plate 17 was observedto have a snug fit within the recesses 172 that was suitable forcreating the mechanical seal. The vacuum source 174 was activated to28.5 millimeters of mercury to effect the pneumatic seal and to pull theplate 17 into registry with the convex surface 126.

For examples 1-4, the mold halves 122, 124 were then closed to make themold cavity 104 using the molding machine 100. The clamping force of themachine 100 used in these examples was 160 tons, and the resin injectionvelocity was 1.5 inches per second. The resin melt temperature of themachine 100 was 585° F., and the mold temperature was 265° F. MoltenLexan® polycarbonate resin was injected into the cavity 104. Lexan®polycarbonate is available from General Electric Plastics Co. ofPittsfield, Mass. After cooling, the mold halves 122, 124 were openedand the lens 10 was ejected from the mold half 122.

For the lenses 10 of Examples 1-4, it was noted that no injectedpolycarbonate flowed between the plate 17 and the convex surface 126.Additionally, no delamination of the functional portion 14 and nowarping of the functional film 21 was observed. Furthermore, thefunctional portion 14 and the power portion 12 were found to be firmlyattached to each other. No voids or inclusions were found anywhere inthe power portion 12, including proximate the functional portion 14.After the inspection, the second sheet 24 of each lens 10 of Examples1-4 was coated with the coating 32 using a conventional dip-coatingtechnique.

Various tests were carried out on the lenses produced in Examples 1-4.The lenses 10 produced in Examples 1-4, referring to FIG. 1, haddiameters F and center thicknesses A as indicated in Table 2 below.Additionally, the design and resultant true curves of the lenses 10 weredetermined to have the values listed in Table 2 using conventionaloptical measurement techniques.

    ______________________________________                                                Lens      Center      Design Resultant                                Example Diameter F                                                                              Thickness A Curve  True Curve                               Number  (mm)      (mm)        (Diopters)                                                                           (Diopters)                               ______________________________________                                        1       75        9.49        2.03   2.04                                     2       75        9.11        2.03   2.04                                     3       75        7.98        4.07   4.05                                     4       75        7.63        4.07   4.09                                     ______________________________________                                    

The resultant true curve of each lens 10 is the optical curve of thelens 10 that is measured between opposite sides 46 of the lens 10 alongthe outside surface 34, as in FIG. 1. The design curve is the tooledcurve of the lens 10, namely the measured curve of the convex surface126 of the mold cavity 104, referring to FIG. 6. Table 2 illustratesthat incorporation of the functional portion 14 into the lens 10 inaccordance with the present invention causes only essentially novariation between the resultant true curve and the design curve for eachof the lenses 10 produced in Examples 1-4.

The lenses 10 made in Examples 1-4 were ground to different finishedprescription focal powers and were then found to have good combinedpower in the spherical and cylindrical axes. Also, the opticalproperties of the lenses 10, including the optical clarity, opticalwave, and optical power, were examined using a conventional lensometerapparatus and were found to be excellent.

The functional portions 14 of each of the lenses 10 were also determinedto be well adhered to the respective power portions 12. Also, thefunctional portions 14 of each of the lenses 10 were tested fordelamination and it was observed that the sheets 22, 24 did notdelaminate from the functional film 21. Additionally, the outsidesurface 34 of each lens 10 was tested for abrasion using the testdetailed in ASTM D 3359-78 and found to exhibit superior abrasionresistance.

Example 5

This example demonstrates formation of the functional film 21 frompolymeric resin and photochromic dye. In this example, the polymericresin was cellulose acetate butyrate, and the photochromic dye was3-(4-biphenylyl)-3-phenyl-8-methoxy-3H-naphtho 2,1b!pyran.

The first step is to blend the resin and the photochromic dye. Toaccomplish this, 0.2 grams of the photochromic dye were mixed with 19.8grams of pelletized cellulose acetate butyrate in a clean, dry, 250 mlglass Erlenmeyer flask. The pelletized cellulose acetate butyrate wasTenite grade 264-E2R300-01, which is available from Eastman Chemical Co.of Kingsport, Tenn. Next, 110.5 grams of n-butyl acetate solvent wereadded to the dye/resin mixture. The Erlenmeyer flask was then placed ina heating container that held a suitable heat transfer fluid, e.g.ethylene glycol or diethylene glycol. The heat transfer fluid was heatedto gradually warm the dye/resin/solvent mixture to 105° C. Thedye/resin/solvent mixture was held at 105° C. and stirred, for aboutfour hours, until the dye and resin dissolved in the solvent and thedye/resin/solvent mixture became homogeneously mixed. The resultant dyesolution was then cooled to room temperature.

A 24"×30"×0.375" piece of float glass was prepared for casting the film21 by first leveling the glass and then cleaning the glass with acetone.Next, a mold release agent was prepared by dissolving one drop ofn-octyl-trichloro-silane into 10 ml of xylene. The mold release agentwas rubbed on the glass using a clean, folded paper tissue that had beendipped in the mold release agent.

A small puddle of the dye solution, at room temperature, was poured fromthe Erlenmeyer flask onto the glass. Promptly thereafter, a GardnerBlade, available from the Paul N. Gardner Company of Pompano Beach,Fla., was drawn over the dye solution at a steady rate to spread auniform sheet of the dye solution across the glass. The n-butyl acetatesolvent was allowed to evaporate for about 24 hours at room temperature,leaving the functional film 21 with the photochromic property on theglass. The functional film 21 was gently removed from the glass by firstpeeling an edge of the film 21 off the glass with the help of a razorblade. The film 21, after evaporation of the solvent, was determined tobe about 0.0013 mm thick.

The film 21 was placed in a spectrometer and the total lighttransmission without activation of the photochromic dye was determinedto be about 92% over the range of the visible spectrum. The total lighttransmission was determined to be about 10% at 480 nm when thephotochromic dye was activated using light provided by a 2.25 mw/cm²ultraviolet lamp. The maximum activation wavelength for the photochromicdye, (3-(4-biphenylyl)-3-phenyl-8-methoxy-3H-naphtho 2,1b!pyran) was 480nm. The ultraviolet lamp was a Bondwand lamp available from EdmundScientific, Inc. of Barrington, N.J.

Example 6

This example demonstrates formation of the functional laminate 19 usingthe functional film 21 produced in Example 5. First, two sheets of3.5"×3.5"×0.010" Makrofol® PCEE polycarbonate (color: "nat"; finish:"EE") was obtained from Bayer, Inc. (formerly Miles, Inc.) ofPittsburgh, Pa. The two polycarbonate sheets, which served as the firstsheet 22 and the second sheet 24, each included protective layers onboth sides of each sheet 22, 24.

The polycarbonate sheet that was to be the first sheet 22 was placed ona hard, flat surface and the protective layer on the side of the sheet22 facing away from the table was removed. Next, the first adhesive 26,which initially consisted of a one inch diameter puddle of Loctite®FMD-436 adhesive, was applied by syringe to the side of the sheet 22that no longer included the protective layer. The functional film 21produced in Example 5 was then carefully placed onto the first adhesive26 and the first sheet 22. A rolling pin was then used to distribute thefirst adhesive 26 at a substantially uniform thickness between the film21 and the sheet 22.

Next, the second adhesive 28, which initially consisted of a one inchdiameter puddle of Loctite® FMD-436 adhesive, was applied by syringe tothe side of the film 21 facing away from the sheet 22. The protectivelayer was then removed from one side of the remaining polycarbonatesheet that was to be the second sheet 24. The side of the sheet 24 notincluding the protective layer was then placed onto the second adhesive28 and the film 21 to form the functional laminate 19. Pressure appliedwith a rolling pin was then used to distribute the second adhesive 28 ata substantially uniform thickness between the film 21 and the sheet 24.

The functional laminate 19 was then placed under a ZETA® 7400ultraviolet lamp, available from Loctite Corporation of Hartford, Conn.,for three minutes per side to cure the first and second adhesives 26,28. The overall thickness of the laminate 19 was determined to be about0.59 mm. The laminate 19 was then placed in a spectrometer and the totallight transmission, without activation of the photochromic dye, wasdetermined to be about 92% over the range of the visible spectrum. Thetotal light transmission was determined to be about 10% at 480 nm whenthe photochromic dye was activated using light provided by theaforementioned Bondwand 2.25 mw/cm² ultraviolet lamp.

Example 7

This example demonstrates formation of the functional film 21 frompolymeric resin and a different photochromic dye from that used inExample 5. The same procedures, quantities, process conditions were usedin this example as in Example 5, with the exception that thephotochromic dye used in this example was Photo "D" photochromic dye, aspiro-oxazine dye available from Great Lakes Chemical, Inc. in Pedrengo,Italy. The maximum activation wavelength for the Photo "D" photochromicdye was 613 nm.

After the n-butyl acetate solvent was allowed to evaporate for about 24hours at room temperature, the functional film 21 with the photochromicproperty remained on the glass. The functional film 21 was gentlyremoved from the glass by first peeling an edge of the film 21 off theglass with the help of a razor blade. The film 21, after evaporation ofthe solvent, was determined to be about 0.001 mm thick.

Example 8

This example demonstrates formation of the functional laminate 19 usingthe same procedure set forth in Example 5, with the exception that thefunctional film 21 produced in Example 7 was used instead of thefunctional film 21 produced in Example 5. The functional laminate 19that was produced in this example using the functional film of Example 7was determined to have an overall thickness of about 0.30 mm. Thelaminate 19 of this example was placed in a spectrometer and the totallight transmission, without activation of the photochromic dye, wasdetermined to be about 92% over the range of the visible spectrum. Thetotal light transmission was determined to be about 20% at 613 nm whenthe photochromic dye was activated using light provided by theaforementioned Bondwand 2.25 mw/cm² ultraviolet lamp.

Example 9

This example demonstrates formation of the lens 10 using the functionallaminate 19 produced in Example 8 to incorporate the photochromicproperty in the lens 10. The first step in making the lens 10 in thisexample was to cut the plate 17 the functional laminate 19 to make thefunctional portion 14. The plate 17 was generally round in shape and hadsubstantially the same dimensions as the surface 18 of the power portion12 to be made. The plate 17, which was not pre-shaped, was placed withinthe recesses 172 so that the second sheet 24 faced the convex surface126. The plate 17 was observed to have a snug fit within the recesses172 that was suitable for creating the mechanical seal. The vacuumsource 174 was activated to 28.5 millimeters of mercury to effect thepneumatic seal and to pull the plate 17 into registry with the convexsurface 126.

The mold halves 122, 124 were then closed to make the mold cavity 104using the molding machine 100. Molten Lexan® polycarbonate resin wasinjected into the cavity 104. The clamping force of the machine 100 usedin this example was 160 tons, and the resin injection velocity was 1.5inches per second. The resin melt temperature of the machine 100 was585° F., and the mold temperature was 265° F.

After cooling, the mold halves 122, 124 were opened and the lens 10 wasejected from the mold half 122. It was noted that no injectedpolycarbonate flowed between the plate 17 and the convex surface 126.Additionally, no delamination of the functional portion 14 and nowarping of the functional film 21 was observed. Furthermore, thefunctional portion 14 and the power portion 12 were found to be firmlyattached to each other. No voids or inclusions were found anywhere inthe power portion 12, including proximate the functional portion 14.After the inspection, the second sheet 24 of the lens 10 was coated withthe coating 32 using a conventional dip-coating technique.

Various tests were carried out on the lens produced in this example. Thelens 10 of this example was placed in a spectrometer and the total lighttransmission, measured through the power portion 12 and the functionalportion 14 without activation of the photochromic dye, was determined tobe about 90% over the range of the visible spectrum. The total lighttransmission measured through the power portion 12 and the functionalportion 14 of the lens 10 was determined to be about 20% at 613 nm whenthe photochromic dye was activated using light provided by theaforementioned Bondwand 2.25 mw/cm² ultraviolet lamp.

The lens 10 was ground to a finished prescription focal power and wasfound to have good combined power in the spherical and cylindrical axes.Also, the optical properties of the lens 10, including the opticalclarity, optical wave, and optical power, were examined using aconventional lensometer apparatus and were found to be excellent.

Also, the functional portion 14 of the lens 10 was tested fordelamination and it was observed that the sheets 22, 24 did notdelaminate from the functional film 21. Additionally, the outsidesurface 34 of the lens 10 was tested for abrasion using the testdetailed in ASTM D 3359-78 and found to exhibit superior abrasionresistance.

Example 10

This example demonstrates formation of the functional film 21 frompolymeric resin and a different photochromic dye from that used inExample 5. The same procedures and process conditions were used in thisexample as in Example 5, with the exception that the amount of thecellulose acetate butyrate used, the amount of the photochromic dyeused, and the composition of the photochromic dye were changed.

The amount of the cellulose acetate butyrate used in this example was19.58 grams. The photochromic dye used in this example was a mixturethat included 0.2 grams of the3-(4-biphenylyl)-3-phenyl-8-methoxy-3H-naphtho 2,1b!pyran photochromicdye used in Example 5, 0.2 grams of the Photo "D" photochromic dye usedin Example 7, and 0.02 grams of Photo "PNO" photochromic dye, which is aspirooxazine dye available from Great Lakes Chemical, Inc. in Pedrengo,Italy. The maximum activation wavelength for the3-(4-biphenylyl)-3-phenyl-8-methoxy-3H-naphtho 2,1b!pyran photochromicdye is 480 nm, the maximum activation wavelength for the Photo "D"photochromic dye is 613 nm, and the maximum activation wavelength forthe Photo "PNO" photochromic dye is 540 nm. When activated withsunlight, this mixture of the three different photochromic dyes achievesa neutral grey color, which is a desirable activated color forophthalmic sunglasses.

After the n-butyl acetate solvent was allowed to evaporate for about 24hours at room temperature, the functional film 21 with the photochromicproperty remained on the glass. The functional film 21 was gentlyremoved from the glass by first peeling an edge of the film 21 off theglass with the help of a razor blade. The film 21, after evaporation ofthe solvent, was determined to be about 0.00122 mm thick.

Example 11

This example demonstrates formation of the functional laminate 19 usingthe same procedure set forth in Example 5, with the exception that thefunctional film 21 produced in Example 10 was used instead of thefunctional film 21 produced in Example 5. The functional laminate 19that was produced in this example using the functional film of Example11 was determined to have an overall thickness of about 0.30 mm. Thelaminate 19 of this example was placed in a spectrometer and the totallight transmission, without activation of the photochromic dye, wasdetermined to be about 90% over the range of the visible spectrum (i.e.:from about 400 nm to about 700 nm). The average total light transmissionwas determined to be about 25% over the range of the visible spectrum(i.e.: from about 400 nm to about 700 nm) when the photochromic dye wasactivated using light provided by the aforementioned Bondwand 2.25mw/cm² ultraviolet lamp.

Example 12

This example demonstrates formation of the lens 10 that is steppedmulti-focal, as in FIG. 4. The lens 10 of FIG. 4 was made using thefunctional laminate 19 produced in Example 11 to incorporate thephotochromic property in the lens 10. The procedures of this examplewere the same as those used in Example 9, with two exceptions. First,the functional laminate 19 of Example 11, rather than the functionallaminate of Example 8, was used in this example. Second, the lens 10 ofFIG. 4, rather than the lens 10 of FIG. 1, was produced in this example.

The convex surface 126 of the molding machine 100 used in this examplewas stepped and discontinuous, as compared to the continuous nature ofthe convex surface 126 of Example 9. The plate 17, which was notpre-shaped, was placed within the recesses 172 so that the second sheet24 faced the convex surface 126. The plate 17 was observed to have asnug fit within the recesses 172 that was suitable for creating themechanical seal. The vacuum source 174 was activated to 28.5 millimetersof mercury to effect the pneumatic seal and to pull the plate 17 intoregistry with the convex surface 126.

The mold halves 122, 124 were then closed to make the mold cavity 104.Molten Lexan® polycarbonate resin was subsequently injected into thecavity 104. After cooling, the mold halves 122, 124 were opened and thelens 10 was ejected from the mold half 122. Upon opening the mold cavity104, it was noted that no injected polycarbonate flowed between theplate 17 and the convex surface 126. Additionally, no delamination ofthe functional portion 14 and no warping of the functional film 21 wasobserved. Also, it was observed that the functional portion 14accurately conformed to the shape of the front surface 18 of the powerportion 12, including the main focal surface 36, the secondary focalsurface 38, and the stepped surface 40 of the power portion.Furthermore, the functional portion 14 and the power portion 12 werefound to be firmly attached to each other. No voids or inclusions werefound anywhere in the power portion 12, including proximate thefunctional portion 14. After the inspection, the second sheet 24 of thelens 10 was coated as specified in Example 9.

Various tests were carried out on the lens produced in this example. Thelens 10 of this example was placed in a spectrometer and the total lighttransmission measured through the power portion 12 and the functionalportion 14 without activation of the photochromic dye, was determined tobe about 90% over the range of the visible spectrum (i.e.: from about400 nm to about 700 nm). The average total light transmission measuredthrough the power portion 12 and the functional portion 14 of the lens10 was determined to be about 25% over the range of the visible spectrum(i.e.: from about 400 nm to about 700 nm) when the photochromic dye wasactivated using light provided by the aforementioned Bondwand 2.25mw/cm² ultraviolet lamp.

The lens 10 of this example was ground to a finished prescription focalpower and was found to have good combined power in the spherical andcylindrical axes. Also, the lens 10 of this example was determined tohave a 6.25 diopter curve with a 1.02 multi-focal additive power.Furthermore, the optical properties of the lens 10, including theoptical clarity, optical wave, and optical power, were examined using aconventional lensometer apparatus and were found to be excellent.

Also, the functional portion 14 of the lens 10 was tested fordelamination and it was observed that the sheets 22, 24 did notdelaminate from the functional film 21. Additionally, the outsidesurface 34 of the lens 10 was tested for abrasion using the testdetailed in ASTM D 3359-78 and found to exhibit superior abrasionresistance.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A method of making an optical element, the methodcomprising:laminating a first thermoplastic resinous sheet and afunctional member; and affixing the first thermoplastic resinous sheetto a power portion of the optical element.
 2. The method of claim 1wherein affixing the first thermoplastic resinous sheet to the powerportion comprises fusing the first thermoplastic resinous sheet to thepower portion.
 3. The method of claim 1 wherein the functional membercomprises:a resinous film; and a functional medium that is incorporatedinto or onto the resinous film.
 4. The method of claim 1 wherein thefunctional member comprises a coating of a functional medium.
 5. Themethod of claim 3, the method further comprising applying a coating ontothe resinous film.
 6. An optical element formed in accordance with themethod of claim
 1. 7. A method of forming an optical element, the methodcomprising:incorporating a functional medium in or on a first discreteresinous layer; placing a second discrete resinous layer in workingrelation with the first discrete resinous layer; and fusing the seconddiscrete resinous layer to a resinous optical component other than thefirst discrete resinous layer.
 8. The method of claim 7 wherein thefunctional medium comprises a photochromic compound and wherein thefirst discrete resinous layer comprises a resin selected from the groupconsisting of cellulose acetate butyrate, poly(n-butyl methacrylate),poly(isobutyl methacrylate), poly(methyl methacrylate), poly(ethylmethacrylate), polyethylene, polypropylene, poly(acrylonitrile),poly(vinyl acetate), poly(vinyl chloride), poly(butadiene), polyamide, acopolymer of any of these, and a mixture of any of these.
 9. The methodof claim 7 wherein the functional medium comprises a light polarizingcomponent and wherein the first discrete resinous layer comprises aresin selected from the group consisting of polyvinyl alcohol,polyvinylformal, polyvinylacetal, saponified (ethylene/vinyl acetate)copolymer, and a mixture of any of these.
 10. An optical element formedin accordance with the method of claim
 7. 11. A method of making amulti-focal lens, the method comprising:forming a power portion of thelens, the power portion having a front side with a main focal surfaceand a secondary focal surface, the secondary focal surface offsetrelative to the main focal surface; and forming a functional portion,the functional portion having a rear side shaped like the front side ofthe power portion; and affixing the rear side of the functional portionto the front side of the power portion.
 12. The method of claim 11wherein affixing the rear side of the functional portion to the frontside of the power portion comprises fusing the rear side of thefunctional portion to the front side of the power portion.
 13. Amulti-focal lens formed in accordance with the method of claim
 11. 14. Amethod of molding an optical element, the method comprising:attaching afunctional member to a first resinous sheet; and placing melted resinousmaterial against the first resinous sheet.
 15. The method of claim 14,the method further comprising:placing the first resinous sheet in a moldcavity of an injection mold; and injecting the melted resinous materialinto the mold cavity and against the first resinous sheet.
 16. Themethod of claim 14 wherein placement of the resinous material againstthe first resinous sheet causes the resinous material and the firstresinous sheet to fuse together.
 17. The method of claim 14 wherein thefunctional member comprises a functional medium that imparts afunctional property to the optical element.
 18. The method of claim 14wherein the first resinous sheet has a first side and a second side, thefunctional member placed against the first side of the first resinoussheet and the melted resinous material placed against the second side ofthe first resinous sheet.
 19. The method of claim 14, the method furthercomprising:incorporating a functional medium onto a second resinoussheet to make the functional member, the functional medium imparting afunctional property to the optical element; and positioning thefunctional medium between the first resinous sheet and the secondresinous sheet.
 20. A method of combining a functional portion with apower portion of an optical element, the method comprising:incorporatinga first thermoplastic material in the functional portion; incorporatinga second thermoplastic material in the power portion; and fusing thepower portion and the functional portion to each other.
 21. The methodof claim 20 wherein the functional portion comprises a light polarizingcomponent or a photochromic compound.
 22. The method of claim 20 whereinthe first thermoplastic material and the second thermoplastic materialare each thermoplastic resinous material.
 23. An optical element formedin accordance with the method of claim
 20. 24. The method of claim 1wherein the power portion supplies a majority of the optical power andmagnification characteristics of the optical element.
 25. The method ofclaim 1 wherein the functional member imparts a functional property tothe optical element.
 26. The method of claim 25 wherein the functionalproperty is selected from the group consisting of photochromism, lightpolarization, hardness, abrasion resistance, chemical resistance, tint,color, decoration, indicia, and any combination of these.
 27. The methodof claim 25 wherein the functional property is selected from the groupconsisting of a light filtering property, a cosmetic property, adurability property, and any combination of these.
 28. The method ofclaim 1 wherein laminating the first thermoplastic resinous sheet andthe functional member comprises applying a functional coating onto thefirst thermoplastic resinous sheet.
 29. The method of claim 3 whereinthe functional medium comprises a light polarizing material and whereinthe resinous film is made of a resin selected from the group consistingof polyvinyl alcohol, polyvinylformal, polyvinylacetal, saponified(ethylene/vinyl acetate) copolymer, and a mixture of any of these. 30.The method of claim 3 wherein the functional medium comprises aphotochromic material and wherein the resinous film is made of a resinselected from the group consisting of cellulose acetate butyrate,poly(n-butyl methacrylate), poly(isobutyl methacrylate), poly(methylmethacrylate), poly(ethyl methacrylate), polyethylene, polypropylene,poly(acrylonitrile), poly(vinyl acetate), poly(vinyl chloride),poly(butadiene), polyamide, a copolymer of any of these, and a mixtureof any of these.
 31. The method of claim 1, the method furthercomprising laminating a resinous film to the functional member, thefunctional member sandwiched between the first thermoplastic resinoussheet and the resinous film.
 32. The method of claim 31 wherein theresinous film consists of a second thermoplastic resinous sheet.
 33. Themethod of claim 1 wherein the first thermoplastic resinous sheet and thepower portion are made of the same thermoplastic material.
 34. Themethod of claim 33 wherein the thermoplastic material is selected fromthe group consisting of polycarbonate, amorphous polyolefin,polystyrene, polyacrylic, a copolymer of any of these, and a mixture ofany of these.
 35. The method of claim 1 wherein the first thermoplasticresinous sheet and the power portion are made of different thermoplasticmaterials.
 36. The method of claim 1 wherein the power portion comprisesa thermoplastic material.
 37. The method of claim 36 wherein:thethermoplastic material is selected from the group consisting ofpolycarbonate, amorphous polyolefin, polystyrene, polyacrylic, acopolymer of any of these, and a mixture of any of these; and the firstthermoplastic resinous sheet is made of a resin selected from the groupconsisting of polycarbonate, amorphous polyolefin, polystyrene,polyacrylic, a copolymer of any of these, and a mixture of any of these.38. The method of claim 1 wherein the optical element is an ophthalmiclens selected from the group consisting of a single vision lens, aprogressive multi-focal lens, an aspheric lens, an aspheric multi-focallens, and a stepped multi-focal lens.
 39. The method of claim 7 whereinthe functional medium imparts a functional property to the opticalelement.
 40. The method of claim 39 wherein the functional property isselected from the group consisting of photochromism, light polarization,hardness, abrasion resistance, chemical resistance, tint, color,decoration, indicia, and any combination of these.
 41. The method ofclaim 39 wherein the functional property is selected from the groupconsisting of a light filtering property, a cosmetic property, adurability property, and any combination of these.
 42. The method ofclaim 7 wherein the resinous optical component comprises a power portionthat supplies a majority of the optical power and magnificationcharacteristics of the optical element, the method further comprisingfusing the second discrete resinous layer to the power portion.
 43. Themethod of claim 42 wherein the power portion and the second discreteresinous layer each comprise thermoplastic resinous material.
 44. Themethod of claim 7 wherein the functional medium is located between thefirst discrete resinous layer and the second discrete resinous layer.45. The method of claim 11 wherein the power portion consists of asingle plastic layer.
 46. The method of claim 11 wherein the powerportion consists of a single thermoplastic resin.
 47. The method ofclaim 11 wherein the main focal surface and the secondary focal surfaceare discontinuous relative to each other.
 48. The method of claim 11wherein the main focal surface and the secondary focal surface define anoffset in the front side of the main focal surface.
 49. The method ofclaim 11 wherein the power portion supplies a majority of the opticalpower and magnification characteristics of the multi-focal lens.
 50. Themethod of claim 14 wherein the first resinous sheet and the meltedresinous material each comprise thermoplastic resin.
 51. The method ofclaim 14, the method further comprising:incorporating a functionalmedium into a second resinous sheet to make the functional member, thefunctional medium imparting a functional property to the opticalelement; and placing the second resinous sheet against the firstresinous sheet.
 52. The method of claim 20 wherein the power portionsupplies a majority of the optical power and magnificationcharacteristics of the optical element.
 53. The method of claim 20wherein the functional member imparts a functional property to theoptical element.
 54. The method of claim 20 wherein the functionalproperty is selected from the group consisting of photochromism, lightpolarization, hardness, abrasion resistance, chemical resistance, tint,color, decoration, indicia, and any combination of these.
 55. The methodof claim 20 wherein the functional property is selected from the groupconsisting of a light filtering property, a cosmetic property, adurability property, and any combination of these.